Republicans fear that a failure to confirm the Supreme Court nominee Brett Kavanaugh could hurt their chance of keeping House and Senate majorities in the midterm elections.

Kavanaugh is facing allegations of sexual misconduct, which is prompting an additional hearing with the Senate Judiciary Committee set for Thursday.

Polling has suggested that Republican voters are already in deep trouble ahead of the elections in November.

WASHINGTON — One of Republicans' biggest selling points on the campaign trail is the record pace of conservative federal judges the Senate has confirmed since Donald Trump became president.

But with the allegations of sexual misconduct against the Supreme Court nominee Brett Kavanaugh putting his confirmation chances on thin ice, the fear of failure is hanging over the heads of many Republicans in tough election bids this November.

The Republican Party base rallied around Trump in 2016 in part because of the nearly yearlong Supreme Court vacancy held open by Senate Majority Leader Mitch McConnell after the death of Justice Antonin Scalia. Now, the GOP must contend with the possibility of Kavanaugh's confirmation falling apart, a move that could be fatal for enthusiasm among the Republican base.

Republican aides and operatives fear that an already unenthusiastic base of GOP voters could be discouraged by Senate Republicans' failure to shepherd Kavanaugh through the confirmation proceedings and onto the Supreme Court.

GOP aides told Business Insider that it was do-or-die with Kavanaugh — something McConnell on Monday made clear was Republicans' highest priority.

"It remains beyond reasonable dispute that Judge Kavanaugh's legal brilliance and excellence on the bench make him one of the very most qualified Supreme Court nominees in the history of our country," McConnell said on the Senate floor. "All these facts are quite clearly on one side. Maybe that's why the Democrats are so panicked. Maybe that's why they are so willing to try to bring down this nominee.

"I want to make it perfectly clear: Judge Kavanaugh will be voted on here on the Senate floor," McConnell added. "Up or down, on the Senate floor, this fine nominee to the Supreme Court will receive a vote in this Senate in the near future."

And it isn't just the political class sounding the alarm about losing the core group of voters that Republicans are depending on to turn out in November — the right-wing talk-radio host Rush Limbaugh warned Republicans of the consequences of not confirming Kavanaugh by Election Day.

"If the Republicans do not get this vote taken and have Kavanaugh confirmed, you can kiss the midterms goodbye," Limbaugh said on his show Monday. "You can kiss goodbye holding the House, and you can kiss goodbye holding the Senate. Because whatever the Democrats think of their base, the one thing I know, that if you guys fold on this and cave and keep bending over backwards ... you've done that enough."

Republican voters are already unenthusiastic going into the November midterm elections

An internal Republican Party poll reflects an already poor environment for the GOP's chances in November.

Bloomberg Businessweek reported that a survey conducted on September 2 for the Republican National Committee found that about half of GOP voters surveyed did not believe that Democrats were likely to win back the House in the midterm elections, despite trends and data that have shown big advantages for Democrats. It suggested that many Republican voters believed Trump when he talked about a "red wave" in 2018.

According to Bloomberg Businessweek, the internal report told Republican officials that they "need to make real the threat that Democrats have a good shot of winning control of Congress" or suffer the consequences.

As a result, Republicans are pulling out all the stops to get behind the embattled nominee.

The Judicial Crisis Network, a group that has put millions behind courting public opinion to confirm both Kavanaugh and Trump's previous Supreme Court pick, Neil Gorsuch, earlier announced a $1.5 million campaign defending Kavanaugh.

On Wednesday — one day before a hearing in which both Kavanaugh and Christine Blasey Ford, who has accused him of sexual assault, are set to testify — the conservative activist group FreedomWorks is holding a rally outside the US Capitol with Republican lawmakers.

"The truth is I've never sexually assaulted anyone, in high school or otherwise," Kavanaugh told the Fox host Martha MacCallum. "I am not questioning and have not questioned that perhaps Dr. Ford at some point in her life was sexually assaulted by someone in some place, but what I know is I've never sexually assaulted anyone."